Bicycle rear sprocket assembly

ABSTRACT

A bicycle rear sprocket assembly comprises at least one sprocket having a total tooth number that is equal to or larger than 15. The at least one sprocket includes at least ten internal spline teeth configured to engage with a bicycle hub assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part application of the U.S. patent application Ser. No. 15/608,924 filed May 30, 2017. The contents of this application are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a bicycle rear sprocket assembly.

Discussion of the Background

Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle. One bicycle component that has been extensively redesigned is a drive train.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention, a bicycle rear sprocket assembly comprises at least one sprocket having a total tooth number that is equal to or larger than 15. The at least one sprocket includes at least ten internal spline teeth configured to engage with a bicycle hub assembly.

With the bicycle rear sprocket assembly according to the first aspect, the at least ten internal spline teeth reduce a rotational force applied to each of the at least ten internal spline teeth in comparison with a sprocket including nine or less internal spline teeth. This improves durability of the at least one sprocket and/or improves a degree of freedom of choosing a material of the at least one sprocket without reducing durability of the at least one sprocket.

In accordance with a second aspect of the present invention, the bicycle rear sprocket assembly according to the first aspect is configured so that a total number of the at least ten internal spline teeth is equal to or larger than 20.

With the bicycle rear sprocket assembly according to the second aspect, the at least twenty internal spline teeth reduce a rotational force applied to each of the at least twenty internal spline teeth in comparison with a sprocket including nine or less internal spline teeth. This improves durability of the at least one sprocket and/or improves a degree of freedom of choosing a material of the at least one sprocket without reducing durability of the at least one sprocket.

In accordance with a third aspect of the present invention, the bicycle rear sprocket assembly according to the second aspect is configured so that the total number of the at least ten internal spline teeth is equal to or larger than 25.

With the bicycle rear sprocket assembly according to the third aspect, the at least twenty-five internal spline teeth further reduce the rotational force applied to each of the at least twenty-five internal spline teeth in comparison with a sprocket including nine or less internal spline teeth. This further improves durability of the at least one sprocket and/or improves a degree of freedom of choosing a material of the at least one sprocket without reducing durability of the at least one sprocket.

In accordance with a fourth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to third aspects is configured so that the at least ten internal spline teeth have a first internal pitch angle and a second internal pitch angle different from the first internal pitch angle.

With the bicycle rear sprocket assembly according to the fourth aspect, the difference between the first internal pitch angle and the second internal pitch angle helps the user to correctly mount the bicycle rear sprocket assembly to the bicycle hub assembly, especially concerning a circumferential position of each sprocket of the bicycle rear sprocket assembly.

In accordance with a fifth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to fourth aspects is configured so that the at least one sprocket includes at least ten sprockets.

With the bicycle rear sprocket assembly according to the fifth aspect, the at least ten sprockets enable a wide range of the bicycle rear sprocket.

In accordance with a sixth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to fourth aspects is configured so that the at least one sprocket includes at least eleven sprockets.

With the bicycle rear sprocket assembly according to the sixth aspect, the at least eleven sprockets enable a wider range of the bicycle rear sprocket.

In accordance with a seventh aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to fourth aspects is configured so that the at least one sprocket includes at least twelve sprockets.

With the bicycle rear sprocket assembly according to the seventh aspect, the at least twelve sprockets enable a wider range of the bicycle rear sprocket.

In accordance with an eighth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to seventh aspects is configured so that the at least one sprocket includes a plurality of sprockets and at least one internal spline tooth configured to engage with a bicycle hub assembly. The plurality of sprockets includes a largest sprocket having a tooth-tip diameter. The at least one internal spline tooth has an internal-spline major diameter. A ratio of the internal-spline major diameter to the tooth-tip diameter ranges from 0.1 to 0.2.

With the bicycle rear sprocket assembly according to the eighth aspect, the ratio enables a wide range of the bicycle rear sprocket assembly with improving durability of the at least one sprocket.

In accordance with a ninth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to eighth aspects is configured so that the at least one sprocket includes a first sprocket and a second sprocket. The first sprocket has a first total tooth number. The second sprocket has a second total tooth number that is smaller than the first total tooth number. The first sprocket includes at least one first shifting facilitation area to facilitate a first shifting operation in which a bicycle chain shifts from the second sprocket to the first sprocket, and at least one second shifting facilitation area to facilitate a second shifting operation in which the bicycle chain shifts from the first sprocket to the second sprocket.

With the bicycle rear sprocket assembly according to the ninth aspect, the at least one first shifting facilitation area and the at least one second shifting facilitation area make the first shifting operation and the second shifting operation smoother.

In accordance with a tenth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to ninth aspects further comprises a lock member configured to prevent an axial movement of the at least one sprocket mounted on a bicycle hub assembly with respect to a rotational center axis of the bicycle rear sprocket assembly. The lock member includes a tubular body portion and a projecting portion. The tubular body portion has a center axis. The projecting portion extends radially outwardly from the tubular body portion with respect to the center axis of the tubular body portion. The tubular body portion has an externally threaded part configured to engage with an internally threaded part of the bicycle hub assembly. The projecting portion is configured to abut against the at least one sprocket.

With the bicycle rear sprocket assembly according to the tenth aspect, it is possible to attach the bicycle rear sprocket assembly to the bicycle hub assembly to prevent the axial movement of the at least one sprocket relative to the bicycle hub assembly.

In accordance with an eleventh aspect of the present invention, the bicycle rear sprocket assembly according to the tenth aspect is configured so that the tubular body portion has a first external diameter that is equal to or smaller than 26 mm.

With the bicycle rear sprocket assembly according to the eleventh aspect, the first external diameter enables a wide range of the bicycle rear sprocket assembly with preventing the axial movement of the at least one sprocket relative to the bicycle hub assembly.

In accordance with a twelfth aspect of the present invention, the bicycle rear sprocket assembly according to the eleventh aspect is configured so that the first external diameter is equal to or larger than 25 mm.

With the bicycle rear sprocket assembly according to the twelfth aspect, the first external diameter ensures strength of the lock member with enabling the wide range of the bicycle rear sprocket assembly.

In accordance with a thirteenth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the tenth to twelfth aspects is configured so that the projecting portion has a second external diameter that is equal to or smaller than 32 mm.

With the bicycle rear sprocket assembly according to the thirteenth aspect, the second external diameter enables a wide range of the bicycle rear sprocket assembly with preventing the axial movement of the at least one sprocket relative to the bicycle hub assembly.

In accordance with a fourteenth aspect of the present invention, the bicycle rear sprocket assembly according to the thirteenth aspect is configured so that the second external diameter is equal to or larger than 30 mm.

With the bicycle rear sprocket assembly according to the fourteenth aspect, the second external diameter ensures strength of the lock member with enabling the wide range of the bicycle rear sprocket assembly.

In accordance with a fifteenth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the tenth to fourteenth aspects is configured so that the lock member has a tool engagement portion.

With the bicycle rear sprocket assembly according to the fifteenth aspect, it is possible to easily attach the lock member to the bicycle hub assembly and to easily detach the lock member from the bicycle hub assembly.

In accordance with a sixteenth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to fifteenth aspects further comprises a sprocket support. The at least one sprocket includes a plurality of sprockets attached to the sprocket support.

With the bicycle rear sprocket assembly according to the sixteenth aspect, it is possible to save weight of the bicycle rear sprocket assembly.

In accordance with a seventeenth aspect of the present invention, the bicycle rear sprocket assembly according to the sixteenth aspect is configured so that the plurality of sprockets is attached to the sprocket support with an adhesive agent.

With the bicycle rear sprocket assembly according to the seventeenth aspect, it is possible to reduce or eliminate a metallic fastener. This effectively saves weight of the bicycle rear sprocket assembly.

In accordance with an eighteenth aspect of the present invention, the bicycle rear sprocket assembly according to the sixteenth or seventeenth aspect is configured so that the sprocket support is made of a non-metallic material including a resin material.

With the bicycle rear sprocket assembly according to the eighteenth aspect, the non-metallic material more effectively saves weight of the bicycle rear sprocket assembly.

In accordance with a nineteenth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the first to eighteenth aspects further comprises a rear-hub abutment surface configured to abut against a bicycle hub assembly in an axial direction with respect to a rotational center axis of the bicycle rear sprocket assembly in a state where the bicycle rear sprocket assembly is mounted to the bicycle hub assembly. The at least one sprocket includes a plurality of sprockets including a largest sprocket. The largest sprocket has an axially inner surface and an axially outer surface provided on a reverse side of the axially inner surface in the axial direction. The axially outer surface is closer to the rear-hub abutment surface than the axially inner surface in the axial direction. An axial distance defined between the axially inner surface and the rear-hub abutment surface in the axial direction is equal to or larger than 7 mm.

With the bicycle rear sprocket assembly according to the nineteenth aspect, the axial distance enables a wide range of the bicycle rear sprocket.

In accordance with a twentieth aspect of the present invention, the bicycle rear sprocket assembly according to the nineteenth aspect is configured so that the axial distance is equal to or larger than 10 mm.

With the bicycle rear sprocket assembly according to the twentieth aspect, the axial distance further enables a wider range of the bicycle rear sprocket.

In accordance with a twenty-first aspect of the present invention, a bicycle rear sprocket assembly comprises at least one sprocket having a total tooth number that is equal to or larger than 15. The at least one sprocket includes at least one internal spline tooth configured to engage with a bicycle hub assembly. The at least one internal spline tooth has an internal-spline major diameter equal to or smaller than 30 mm.

With the bicycle rear sprocket assembly according to the twenty-first aspect, it is possible to manufacture a bicycle rear sprocket with a total tooth number that is equal to or smaller than 10. Therefore, it is possible to widen a gear range of the bicycle rear sprocket assembly on a top gear side. The twenty-first aspect can be combined with any one of the first to twentieth aspects.

In accordance with a twenty-second aspect of the present invention, the bicycle rear sprocket assembly according to the twenty-first aspect is configured so that the internal-spline major diameter is equal to or larger than 25 mm.

With the bicycle rear sprocket assembly according to the twenty-second aspect, it is possible to ensure strength of the at least one sprocket with widening the gear range of the bicycle rear sprocket assembly on a top gear side.

In accordance with a twenty-third aspect of the present invention, the bicycle rear sprocket assembly according to the twenty-first aspect is configured so that the internal-spline major diameter is equal to or larger than 29 mm.

With the bicycle rear sprocket assembly according to the twenty-third aspect, it is possible to further ensure strength of the at least one sprocket with widening the gear range of the bicycle rear sprocket assembly on a top gear side.

In accordance with a twenty-fourth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the twenty-first to twenty-third aspects is configured so that the at least one internal spline tooth has an internal-spline minor diameter equal to or smaller than 28 mm.

With the bicycle rear sprocket assembly according to the twenty-fourth aspect, the internal-spline minor diameter can increase a radial length of a driving surface of the at least one internal spline tooth. This improves strength of the at least one sprocket.

In accordance with a twenty-fifth aspect of the present invention, the bicycle rear sprocket assembly according to the twenty-fourth aspect is configured so that the internal-spline minor diameter is equal to or larger than 25 mm.

With the bicycle rear sprocket assembly according to the twenty-fifth aspect, it is possible to ensure strength of the at least one sprocket with widening the gear range of the bicycle rear sprocket assembly on a top gear side.

In accordance with a twenty-sixth aspect of the present invention, the bicycle rear sprocket assembly according to the twenty-fourth or twenty-fifth aspect is configured so that the internal-spline minor diameter is equal to or larger than 27 mm.

With the bicycle rear sprocket assembly according to the twenty-sixth aspect, it is possible to certainly ensure strength of the at least one sprocket with widening the gear range of the bicycle rear sprocket assembly on a top gear side.

In accordance with a twenty-seventh aspect of the present invention, the bicycle rear sprocket assembly according to any one of the twenty-first to twenty sixth aspects is configured so that the at least one internal spline tooth includes a plurality of internal spline teeth including a plurality of internal-spline driving surfaces to receive a driving rotational force from the bicycle hub assembly during pedaling. The plurality of internal-spline driving surfaces each includes a radially outermost edge, a radially innermost edge, and a radial length defined from the radially outermost edge to the radially innermost edge. A total of the radial lengths is equal to or larger than 7 mm.

With the bicycle rear sprocket assembly according to the twenty-seventh aspect, it is possible to increase the radial lengths of the plurality of internal-spline driving surface. This improves strength of the at least one sprocket.

In accordance with a twenty-eighth aspect of the present invention, the bicycle rear sprocket assembly according to the twenty-seventh aspect is configured so that the total of the radial lengths is equal to or larger than 10 mm.

With the bicycle rear sprocket assembly according to the twenty-eighth aspect, it is possible to further increase the radial lengths of the plurality of internal-spline driving surface. This improves strength of the at least one sprocket.

In accordance with a twenty-ninth aspect of the present invention, the bicycle rear sprocket assembly according to the twenty-seventh aspect is configured so that the total of the radial lengths is equal to or larger than 15 mm.

With the bicycle rear sprocket assembly according to the twenty-ninth aspect, it is possible to further increase the radial lengths of the plurality of external-spline driving surface. This further improves strength of the at least one sprocket.

In accordance with a thirtieth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the twenty-first to twenty-ninth aspects is configured so that the at least one sprocket includes at least ten sprockets.

With the bicycle rear sprocket assembly according to the thirtieth aspect, the at least ten sprocket enables a wide range of the bicycle rear sprocket assembly.

In accordance with a thirty-first aspect of the present invention, the bicycle rear sprocket assembly according to any one of the twenty-first to twenty-ninth aspects is configured so that the at least one sprocket includes at least eleven sprockets.

With the bicycle rear sprocket assembly according to the thirty-first aspect, the at least eleven sprocket enables a wide range of the bicycle rear sprocket assembly.

In accordance with a thirty-second aspect of the present invention, the bicycle rear sprocket assembly according to any one of the twenty-first to twenty-ninth aspects is configured so that the at least one sprocket includes at least twelve sprockets.

With the bicycle rear sprocket assembly according to the thirty-second aspect, the at least twelve sprocket enables a wide range of the bicycle rear sprocket assembly.

In accordance with a thirty-third aspect of the present invention, the bicycle rear sprocket assembly according to any one of the twenty-first to thirty-second aspects is configured so that the at least one sprocket includes a plurality of sprockets. The plurality of sprockets includes a largest sprocket having a tooth-tip diameter. A ratio of the internal-spline major diameter to the tooth-tip diameter ranges from 0.1 to 0.2.

With the bicycle rear sprocket assembly according to the thirty-third aspect, the ratio enables a wide range of the bicycle rear sprocket assembly with improving durability of the at least one sprocket.

In accordance with a thirty-fourth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the twenty-first to thirty-third aspects is configured so that the at least one sprocket includes a first sprocket and a second sprocket. The first sprocket has a first total tooth number. The second sprocket has a second total tooth number that is smaller than the first total tooth number. The first sprocket includes at least one first shifting facilitation area to facilitate a first shifting operation in which a bicycle chain shifts from the second sprocket to the first sprocket, and at least one second shifting facilitation area to facilitate a second shifting operation in which the bicycle chain shifts from the first sprocket to the second sprocket.

With the bicycle rear sprocket assembly according to the thirty-fourth aspect, the at least one first shifting facilitation area and the at least one second shifting facilitation area make the first shifting operation and the second shifting operation smoother.

In accordance with a thirty-fifth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the twenty-first to thirty-fourth aspects further comprises a lock member configured to prevent an axial movement of the at least one sprocket mounted on a bicycle hub assembly with respect to a rotational center axis of the bicycle rear sprocket assembly. The lock member includes a tubular body portion and a projecting portion. The tubular body portion has a center axis. The projecting portion extends radially outwardly from the tubular body portion with respect to the center axis of the tubular body portion. The tubular body portion has an externally threaded part configured to engage with an internally threaded part of the bicycle hub assembly. The projecting portion is configured to abut against the at least one sprocket.

With the bicycle rear sprocket assembly according to the thirty-fifth aspect, it is possible to attach the bicycle rear sprocket assembly to the bicycle hub assembly to prevent the axial movement of the at least one sprocket relative to the bicycle hub assembly.

In accordance with a thirty-sixth aspect of the present invention, the bicycle rear sprocket assembly according to the thirty-fifth aspect is configured so that the tubular body portion has a first external diameter that is equal to or smaller than 26 mm.

With the bicycle rear sprocket assembly according to the thirty-sixth aspect, the first external diameter enables a wide range of the bicycle rear sprocket assembly with preventing the axial movement of the at least one sprocket relative to the bicycle hub assembly.

In accordance with a thirty-seventh aspect of the present invention, the bicycle rear sprocket assembly according to the thirty-sixth aspect is configured so that the first external diameter is equal to or larger than 25 mm.

With the bicycle rear sprocket assembly according to the thirty-seventh aspect, the first external diameter ensures strength of the lock member with enabling the wide range of the bicycle rear sprocket assembly.

In accordance with a thirty-eighth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the thirty-fifth to thirty-seventh aspects is configured so that the projecting portion has a second external diameter that is equal to or smaller than 32 mm.

With the bicycle rear sprocket assembly according to the thirty-eighth aspect, the second external diameter enables a wide range of the bicycle rear sprocket assembly with preventing the axial movement of the at least one sprocket relative to the bicycle hub assembly.

In accordance with a thirty-ninth aspect of the present invention, the bicycle rear sprocket assembly according to the thirty-eighth aspect is configured so that the second external diameter is equal to or larger than 30 mm.

With the bicycle rear sprocket assembly according to the thirty-ninth aspect, the second external diameter ensures strength of the lock member with enabling the wide range of the bicycle rear sprocket assembly.

In accordance with a fortieth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the thirty-fifth to thirty-ninth aspects is configured so that the lock member has a tool engagement portion.

With the bicycle rear sprocket assembly according to the fortieth aspect, it is possible to easily attach the lock member to the bicycle hub assembly and to easily detach the lock member from the bicycle hub assembly.

In accordance with a forty-first aspect of the present invention, the bicycle rear sprocket assembly according to any one of the twenty-first to fortieth aspects further comprises a sprocket support. The at least one sprocket includes a plurality of sprockets attached to the sprocket support.

With the bicycle rear sprocket assembly according to the forty-first aspect, it is possible to save weight of the bicycle rear sprocket assembly.

In accordance with a forty-second aspect of the present invention, the bicycle rear sprocket assembly according to the forty-first aspect is configured so that the plurality of sprockets is attached to the sprocket support with an adhesive agent.

With the bicycle rear sprocket assembly according to the forty-second aspect, it is possible to reduce or eliminate a metallic fastener. This effectively saves weight of the bicycle rear sprocket assembly.

In accordance with a forty-third aspect of the present invention, the bicycle rear sprocket assembly according to the forty-first or forty-second aspect is configured so that the sprocket support is made of a non-metallic material including a resin material.

With the bicycle rear sprocket assembly according to the forty-third aspect, the non-metallic material more effectively saves weight of the bicycle rear sprocket assembly.

In accordance with a forty-fourth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the twenty-first to forty-third aspects further comprises a rear-hub abutment surface configured to abut against a bicycle hub assembly in an axial direction with respect to a rotational center axis of the bicycle rear sprocket assembly in a state where the bicycle rear sprocket assembly is mounted to the bicycle hub assembly. The at least one sprocket includes a plurality of sprockets including a largest sprocket. The largest sprocket has an axially inner surface and an axially outer surface provided on a reverse side of the axially inner surface in the axial direction. The axially outer surface is closer to the rear-hub abutment surface than the axially inner surface in the axial direction. An axial distance defined between the axially inner surface and the rear-hub abutment surface in the axial direction is equal to or larger than 7 mm.

With the bicycle rear sprocket assembly according to the forty-fourth aspect, the axial distance enables a wide range of the bicycle rear sprocket.

In accordance with a forty-fifth aspect of the present invention, the bicycle rear sprocket assembly according to the forty-fourth aspect is configured so that the axial distance is equal to or larger than 10 mm.

With the bicycle rear sprocket assembly according to the forty-fifth aspect, the axial distance further enables a wider range of the bicycle rear sprocket.

In accordance with a forty-sixth aspect of the present invention, a bicycle rear sprocket assembly comprises a plurality of sprockets, a rear-hub abutment surface, and an axial distance. The plurality of sprockets includes a largest sprocket. The largest sprocket has an axially inner surface and an axially outer surface provided on a reverse side of the axially inner surface in an axial direction with respect to a rotational center axis of the bicycle rear sprocket assembly. The rear-hub abutment surface is configured to abut against a bicycle hub assembly in the axial direction in a state where the bicycle rear sprocket assembly is mounted to the bicycle hub assembly, the axially outer surface being closer to the rear-hub abutment surface than the axially inner surface in the axial direction. The axial distance defined between the axially inner surface and the rear-hub abutment surface in the axial direction is equal to or larger than 7 mm.

With the bicycle rear sprocket assembly according to the forty-sixth aspect, the axial distance enables a wide range of the bicycle rear sprocket.

In accordance with a forty-seventh aspect of the present invention, the bicycle rear sprocket assembly according to the forty-sixth aspect is configured so that the axial distance is equal to or larger than 10 mm.

With the bicycle rear sprocket assembly according to the forty-seventh aspect, the axial distance further enables a wider range of the bicycle rear sprocket.

In accordance with a forty-eighth aspect of the present invention, the bicycle rear sprocket assembly according to the forty-sixth or forty-seventh aspect is configured so that the axially inner surface is positioned closer to an axial center plane of the bicycle hub assembly than the rear-hub abutment surface in a state where the bicycle rear sprocket assembly is mounted to the bicycle hub assembly.

With the bicycle rear sprocket assembly according to the forty-eighth aspect, the axial distance enables a wider range of the bicycle rear sprocket.

In accordance with a forty-ninth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the forty-sixth to forty-eighth aspects is configured so that a total number of the plurality of sprockets is 12.

With the bicycle rear sprocket assembly according to the forty-ninth aspect, the total number of the plurality of sprockets enables a wide range of the bicycle rear sprocket.

In accordance with a fiftieth aspect of the present invention, the bicycle rear sprocket assembly according to any one of the forty-sixth to forty-ninth aspects is configured so that a total tooth number of the largest sprocket is equal to or larger than 39.

With the bicycle rear sprocket assembly according to the fiftieth aspect, the total tooth number of the largest sprocket enables a wide range of the bicycle rear sprocket.

In accordance with a fifty-first aspect of the present invention, the bicycle rear sprocket assembly according to any one of the forty-sixth to forty-ninth aspects is configured so that a total tooth number of the largest sprocket is equal to or larger than 45.

With the bicycle rear sprocket assembly according to the fifty-first aspect, the total tooth number of the largest sprocket enables a wider range of the bicycle rear sprocket.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

FIG. 1 is a schematic diagram of a bicycle drive train in accordance with an embodiment.

FIG. 2 is an exploded perspective view of the bicycle drive train illustrated in FIG. 1.

FIG. 3 is another perspective view of the bicycle drive train illustrated in FIG. 2.

FIG. 4 is a cross-sectional view of the bicycle drive train taken along line IV-IV of FIG. 2.

FIG. 5 is an exploded perspective view of a bicycle hub assembly of the bicycle drive train illustrated in FIG. 2.

FIG. 6 is an enlarged cross-sectional view of the bicycle drive train illustrated in FIG. 4.

FIG. 7 is a perspective view of a sprocket support body of the bicycle hub assembly of the bicycle drive train illustrated in FIG. 2.

FIG. 8 is another perspective view of the sprocket support body of the bicycle hub assembly of the bicycle drive train illustrated in FIG. 2.

FIG. 9 is a side elevational view of the sprocket support body illustrated in FIG. 7.

FIG. 10 is a side elevational view of a sprocket support body of the bicycle hub assembly in accordance with a modification.

FIG. 11 is an enlarged cross-sectional view of the sprocket support body illustrated in FIG. 7.

FIG. 12 is a cross-sectional view of the sprocket support body illustrated in FIG. 7.

FIG. 13 is a perspective view of the bicycle hub assembly of the bicycle drive train illustrated in FIG. 2.

FIG. 14 is a side elevational view of the bicycle hub assembly of the bicycle drive train illustrated in FIG. 2.

FIG. 15 is a rear view of the bicycle hub assembly of the bicycle drive train illustrated in FIG. 2.

FIG. 16 is a cross-sectional view of the bicycle hub assembly taken along line XVI-XVI of FIG. 5.

FIG. 17 is a side elevational view of the bicycle rear sprocket assembly of the bicycle drive train illustrated in FIG. 2.

FIG. 18 is an exploded perspective view of the bicycle rear sprocket assembly illustrated in FIG. 17.

FIG. 19 is a partial exploded perspective view of the bicycle rear sprocket assembly illustrated in FIG. 17.

FIG. 20 is another partial exploded perspective view of the bicycle rear sprocket assembly illustrated in FIG. 17.

FIG. 21 is another partial exploded perspective view of the bicycle rear sprocket assembly illustrated in FIG. 17.

FIG. 22 is another partial exploded perspective view of the bicycle rear sprocket assembly illustrated in FIG. 17.

FIG. 23 is a perspective cross-sectional view of the bicycle rear sprocket assembly taken along line XXIII-XXIII of FIG. 17.

FIG. 24 is a perspective view of a smallest sprocket of the bicycle rear sprocket assembly illustrated in FIG. 17.

FIG. 25 is another perspective view of the smallest sprocket of the bicycle rear sprocket assembly illustrated in FIG. 17.

FIG. 26 is a side elevational view of the smallest sprocket of the bicycle rear sprocket assembly illustrated in FIG. 17.

FIG. 27 is a side elevational view of a smallest sprocket in accordance with a modification.

FIG. 28 is an enlarged cross-sectional view of the smallest sprocket illustrated in FIG. 24.

FIG. 29 is a cross-sectional view of the smallest sprocket illustrated in FIG. 24.

FIG. 30 is a cross-sectional view of the sprocket support body and the smallest sprocket of the bicycle drive train illustrated in FIG. 2.

FIG. 31 is a partial exploded perspective view of the bicycle rear sprocket assembly illustrated in FIG. 17.

FIG. 32 is a perspective view of a sprocket support of the bicycle rear sprocket assembly illustrated in FIG. 17.

FIG. 33 is a side elevational view of a bicycle rear sprocket assembly in accordance with a modification.

FIG. 34 is a side elevational view of a first sprocket of the bicycle rear sprocket assembly illustrated in FIG. 33.

FIG. 35 is a partial perspective view of the first sprocket of the bicycle rear sprocket assembly illustrated in FIG. 33.

FIG. 36 is another side elevational view of a first sprocket of the bicycle rear sprocket assembly illustrated in FIG. 33.

FIG. 37 is another partial perspective view of the first sprocket of the bicycle rear sprocket assembly illustrated in FIG. 33.

FIG. 38 is an enlarged cross-sectional view of the sprocket support body in accordance with a modification.

FIG. 39 is an enlarged cross-sectional view the smallest sprocket in accordance with a modification.

DESCRIPTION OF THE EMBODIMENTS

The embodiment(s) will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings.

Referring initially to FIG. 1, a bicycle drive train 10 in accordance with an embodiment comprises a bicycle hub assembly 12 and a bicycle rear sprocket assembly 14. The bicycle hub assembly 12 is secured to a bicycle frame BF. The bicycle rear sprocket assembly 14 is mounted on the bicycle hub assembly 12. A bicycle brake rotor 16 is mounted on the bicycle hub assembly 12.

The bicycle drive train 10 further comprises a crank assembly 18 and a bicycle chain 20. The crank assembly 18 includes a crank axle 22, a right crank arm 24, a left crank arm 26, and a front sprocket 27. The right crank arm 24 and the left crank arm 26 are secured to the crank axle 22. The front sprocket 27 is secured to at least one of the crank axle 22 and the right crank arm 24. The bicycle chain 20 is engaged with the front sprocket 27 and the bicycle rear sprocket assembly 14 to transmit a pedaling force from the front sprocket 27 to the bicycle rear sprocket assembly 14. The crank assembly 18 includes the front sprocket 27 as a single sprocket in the illustrated embodiment. However, the crank assembly 18 can include a plurality of front sprockets. The bicycle rear sprocket assembly 14 is a rear sprocket assembly. However, structures of the bicycle rear sprocket assembly 14 can be applied to the front sprocket.

In the present application, the following directional terms “front,” “rear,” “forward,” “rearward,” “left,” “right,” “transverse,” “upward” and “downward” as well as any other similar directional terms refer to those directions which are determined on the basis of a user (e.g., a rider) who sits on a saddle (not shown) of a bicycle with facing a handlebar (not shown). Accordingly, these terms, as utilized to describe the bicycle drive train 10, the bicycle hub assembly 12, or the bicycle rear sprocket assembly 14, should be interpreted relative to the bicycle equipped with the bicycle drive train 10, the bicycle hub assembly 12, or the bicycle rear sprocket assembly 14 as used in an upright riding position on a horizontal surface.

As seen in FIGS. 2 and 3, the bicycle hub assembly 12 and the bicycle rear sprocket assembly 14 have a rotational center axis A1. The bicycle rear sprocket assembly 14 is rotatably supported by the bicycle hub assembly 12 relative to the bicycle frame BF (FIG. 1) about the rotational center axis A1. The bicycle rear sprocket assembly 14 is configured to be engaged with the bicycle chain 20 to transmit a driving rotational force F1 between the bicycle chain 20 and the bicycle rear sprocket assembly 14 during pedaling. The bicycle rear sprocket assembly 14 is rotated about the rotational center axis A1 in a driving rotational direction D11 during pedaling. The driving rotational direction D11 is defined along a circumferential direction D1 of the bicycle hub assembly 12 or the bicycle rear sprocket assembly 14. A reverse rotational direction D12 is an opposite direction of the driving rotational direction D11 and is defined along the circumferential direction D1.

As seen in FIG. 2, the bicycle hub assembly 12 comprises a sprocket support body 28. The bicycle rear sprocket assembly 14 is mounted on the sprocket support body 28 to transmit the driving rotational force F1 between the sprocket support body 28 and the bicycle rear sprocket assembly 14. The bicycle hub assembly 12 further comprises a hub axle 30. The sprocket support body 28 is rotatably mounted on the hub axle 30 about the rotational center axis A1. The bicycle rear sprocket assembly 14 further comprises a lock member 32. The lock member 32 is secured to the sprocket support body 28 to hold the bicycle rear sprocket assembly 14 relative to the sprocket support body 28 in an axial direction D2 parallel to the rotational center axis A1.

As seen in FIG. 4, the bicycle hub assembly 12 is secured to the bicycle frame BF with a wheel securing structure WS. The hub axle 30 has a through hole 30A. A securing rod WS1 of the wheel securing structure WS extends through the through hole 30A of the hub axle 30. The hub axle 30 includes a first axle end 30B and a second axle end 30C. The hub axle 30 extends between the first axle end 30B and the second axle end 30C along the rotational center axis A1. The first axle end 30B is provided in a first recess BF11 of a first frame BF1 of the bicycle frame BF. The second axle end 30C is provided in a second recess BF21 of a second frame BF2 of the bicycle frame BF. The hub axle 30 is held between the first frame BF1 and the second frame BF2 with the wheel securing structure WS. The wheel securing structure WS includes a structure which has been known in the bicycle filed. Thus, it will not be described in detail here for the sake of brevity.

As seen in FIGS. 4 and 5, the bicycle hub assembly 12 further comprises a brake-rotor support body 34. The brake-rotor support body 34 is rotatably mounted on the hub axle 30 about the rotational center axis A1. The brake-rotor support body 34 is coupled to the bicycle brake rotor 16 (FIG. 1) to transmit a braking rotational force from the bicycle brake rotor 16 to the brake-rotor support body 34.

As seen in FIG. 5, the bicycle hub assembly 12 further comprises a hub body 36. The hub body 36 is rotatably mounted on the hub axle 30 about the rotational center axis A1. In this embodiment, the sprocket support body 28 is a separate member from the hub body 36. The brake-rotor support body 34 is integrally provided with the hub body 36 as a one-piece unitary member. However, the sprocket support body 28 can be integrally provided with the hub body 36. The brake-rotor support body 34 can be a separate member from the hub body 36.

The hub body 36 includes a first flange 36A and a second flange 36B. First spokes (not shown) are coupled to the first flange 36A. Second spokes (not shown) are coupled to the second flange 36B. The second flange 36B is spaced apart from the first flange 36A in the axial direction D2. The first flange 36A is provided between the sprocket support body 28 and the second flange 36B in the axial direction D2. The second flange 36B is provided between the first flange 36A and the brake-rotor support body 34 in the axial direction D2.

The lock member 32 includes an externally threaded part 32A. The sprocket support body 28 includes an internally threaded part 28A. The externally threaded part 32A is threadedly engaged with the internally threaded part 28A in a state where the lock member 32 is secured to the sprocket support body 28.

As seen in FIG. 6, the lock member 32 is configured to prevent an axial movement of the at least one sprocket mounted on the bicycle hub assembly 12 with respect to the rotational center axis A1 of the bicycle rear sprocket assembly 14. As seen in FIG. 5, the lock member 32 includes a tubular body portion 32C and a projecting portion 32B. The tubular body portion 32C has a center axis A2. The projecting portion 32B extends radially outwardly from the tubular body portion 32C with respect to the center axis A2 of the tubular body portion 32C. The tubular body portion 32C has the externally threaded part 32A configured to engage with the internally threaded part 28A of the bicycle hub assembly 12.

As seen in FIG. 6, the projecting portion 32B is configured to abut against the at least one sprocket. In this embodiment, the projecting portion 32B is configured to abut against the sprocket SP1. The tubular body portion 32C has a first external diameter ED1 that is equal to or smaller than 26 mm. The first external diameter ED1 is equal to or larger than 25 mm. In this embodiment, the first external diameter ED1 is 25.45 mm. However, the first external diameter ED1 is not limited to this embodiment and the above ranges. The projecting portion 32B has a second external diameter ED2 that is equal to or smaller than 32 mm. The second external diameter ED2 is equal to or larger than 30 mm. In this embodiment, the second external diameter ED2 is 31.5 mm. However, the second external diameter ED2 is not limited to this embodiment and the above ranges.

As seen in FIG. 5, the lock member 32 has a tool engagement portion 32D. The tool engagement portion 32D is provided on an inner peripheral surface 32C1 of the tubular body portion 32C to be engaged with a tool. The tool engagement portion 32D includes a plurality of tool engagement recesses 32D1 provided on the inner peripheral surface 32C1 of the tubular body portion 32C. However, the structure of the tool engagement portion 32D is not limited to this embodiment. The tool engagement portion 32D can be omitted from the lock member 32 or can have another shape that is different from the tool engagement portion 32D in the illustrated embodiment.

As seen in FIG. 6, the bicycle hub assembly 12 further comprises a ratchet structure 38. The sprocket support body 28 is operatively coupled to the hub body 36 with the ratchet structure 38. The ratchet structure 38 is configured to couple the sprocket support body 28 to the hub body 36 to rotate the sprocket support body 28 along with the hub body 36 in the driving rotational direction D11 (FIG. 5) during pedaling. The ratchet structure 38 is configured to allow the sprocket support body 28 to rotate relative to the hub body 36 in the reverse rotational direction D12 (FIG. 5) during coasting. Accordingly, the ratchet structure 38 may be paraphrased into a one-way clutch structure 38. The ratchet structure 38 includes structures which have been known in the bicycle field. Thus, they will not be described in detail here for the sake of brevity.

The bicycle hub assembly 12 includes a first bearing 39A and a second bearing 39B. The first bearing 39A and the second bearing 39B are provided between the sprocket support body 28 and the hub axle 30 to rotatably support the sprocket support body 28 relative to the hub axle 30 about the rotational center axis A1.

In this embodiment, each of the sprocket support body 28, the brake-rotor support body 34, and the hub body 36 is made of a metallic material such as aluminum, iron, or titanium. However, at least one of the sprocket support body 28, the brake-rotor support body 34, and the hub body 36 can be made of a non-metallic material.

As seen in FIGS. 7 and 8, the sprocket support body 28 includes at least one external spline tooth 40 configured to engage with the bicycle rear sprocket assembly 14 (FIG. 6). The sprocket support body 28 includes a plurality of external spline teeth 40 configured to engage with the bicycle rear sprocket assembly 14 (FIG. 6). Namely, the at least one external spline tooth 40 includes a plurality of external spline teeth 40. The sprocket support body 28 includes at least nine external spline teeth 40 configured to engage with the bicycle rear sprocket assembly 14 (FIG. 6). The sprocket support body 28 includes at least ten external spline teeth 40 configured to engage with the bicycle rear sprocket assembly 14 (FIG. 6).

The sprocket support body 28 includes a base support 41 having a tubular shape. The base support 41 extends along the rotational center axis A1. The external spline tooth 40 extends radially outwardly from the base support 41. The sprocket support body 28 includes a larger-diameter part 42, a flange 44, and a plurality of helical external spline teeth 46. The larger-diameter part 42 and the flange 44 extend radially outwardly from the base support 41. The larger-diameter part 42 is provided between the plurality of external spline teeth 40 and the flange 44 in the axial direction D2. The larger-diameter part 42 and the flange 44 are provided between the plurality of external spline teeth 40 and the plurality of helical external spline teeth 46 in the axial direction D2. As seen in FIG. 6, the bicycle rear sprocket assembly 14 is held between the larger-diameter part 42 and the projecting portion 32B of the lock member 32 in the axial direction D2. The larger-diameter part 42 may have an interior cavity so that a drive structure such as a one-way clutch structure can be contained within the interior cavity. The larger-diameter part 42 can be omitted from the bicycle hub assembly 12 according to need.

As seen in FIG. 9, a total number of the at least ten external spline teeth 40 is equal to or larger than 20. The total number of the at least ten external spline teeth 40 is equal to or larger than 25. In this embodiment, the total number of the at least ten external spline teeth 40 is 26. However, a total number of the external spline teeth 40 is not limited to this embodiment and the above ranges.

The at least ten external spline teeth 40 have a first external pitch angle PA11 and a second external pitch angle PA12. At least two external spline teeth of the plurality of external spline teeth 40 are circumferentially arranged at the first external pitch angle PA11 with respect to the rotational center axis A1 of the bicycle hub assembly 12. At least two external spline teeth of the plurality of external spline teeth 40 are circumferentially arranged at the second external pitch angle PA12 with respect to the rotational center axis A1 of the bicycle hub assembly 12. In this embodiment, the second external pitch angle PA12 is different from the first external pitch angle PA11. However, the second external pitch angle PA12 can be substantially equal to the first external pitch angle PA11.

In this embodiment, the external spline teeth 40 are arranged at the first external pitch angle PA11 in the circumferential direction D1. Two external spline teeth of the external spline teeth 40 are arranged at the second external pitch angle PA12 in the circumferential direction D1. However, at least two external spline teeth of the external spline teeth 40 can be arranged at another external pitch angle in the circumferential direction D1.

The first external pitch angle PA11 ranges from 10 degrees to 20 degrees. The first external pitch angle PA11 ranges from 12 degrees to 15 degrees. The first external pitch angle PA11 ranges from 13 degrees to 14 degrees. In this embodiment, the first external pitch angle PA11 is 13.3 degrees. However, the first external pitch angle PA11 is not limited to this embodiment and the above ranges.

The second external pitch angle PA12 ranges from 5 degrees to 30 degrees. In this embodiment, the second external pitch angle PA12 is 26 degrees. However, the second external pitch angle PA12 is not limited to this embodiment and the above range.

The external spline teeth 40 have substantially the same shape as each other. The external spline teeth 40 have substantially the same spline size as each other. The external spline teeth 40 have substantially the same profile as each other when viewed along the rotational center axis A1. As seen in FIG. 10, however, at least one of the at least ten external spline teeth 40 can have a first spline shape different from a second spline shape of another of the at least ten external spline teeth 40. At least one of the at least ten external spline teeth 40 can have a first spline size different from a second spline size of another of the at least ten external spline teeth 40. At least one of the at least ten external spline teeth 40 can have a profile different from a profile of another of the at least ten external spline teeth 40 when viewed along the rotational center axis A1. In FIG. 10, one of the external spline teeth 40 has a spline shape different from a spline shape of the other teeth of the external spline teeth 40. One of the external spline teeth 40 has a spline size different from a spline size of the other teeth of the external spline teeth 40. One of the external spline teeth 40 has a profile different from a profile of the other teeth of the external spline teeth 40 when viewed along the rotational center axis A1.

As seen in FIG. 11, each of the at least ten external spline teeth 40 has an external-spline driving surface 48 and an external-spline non-driving surface 50. The plurality of external spline teeth 40 includes a plurality of external-spline driving surfaces 48 to receive the driving rotational force F1 from the bicycle rear sprocket assembly 14 (FIG. 6) during pedaling. The plurality of external spline teeth 40 includes a plurality of external-spline non-driving surfaces 50. The external-spline driving surface 48 is contactable with the bicycle rear sprocket assembly 14 to receive the driving rotational force F1 from the bicycle rear sprocket assembly 14 (FIG. 6) during pedaling. The external-spline driving surface 48 faces in the reverse rotational direction D12. The external-spline non-driving surface 50 is provided on a reverse side of the external-spline driving surface 48 in the circumferential direction D1. The external-spline non-driving surface 50 faces in the driving rotational direction D11 not to receive the driving rotational force F1 from the bicycle rear sprocket assembly 14 during pedaling.

The at least ten external spline teeth 40 respectively have circumferential maximum widths MW1. The external spline teeth 40 respectively have circumferential maximum widths MW1. The circumferential maximum width MW1 is defined as a maximum width to receive a thrust force F2 applied to the external spline tooth 40. The circumferential maximum width MW1 is defined as a straight distance based on the external-spline driving surface 48.

The plurality of external-spline driving surfaces 48 each includes a radially outermost edge 48A and a radially innermost edge 48B. The external-spline driving surface 48 extends from the radially outermost edge 48A to the radially innermost edge 48B. A first reference circle RC11 is defined on the radially innermost edge 48B and is centered at the rotational center axis A1. The first reference circle RC11 intersects with the external-spline non-driving surface 50 at a reference point 50R. The circumferential maximum width MW1 extends straight from the radially innermost edge 48B to the reference point 50R in the circumferential direction D1.

The plurality of external-spline non-driving surfaces 50 each includes a radially outermost edge 50A and a radially innermost edge 50B. The external-spline non-driving surface 50 extends from the radially outermost edge 50A to the radially innermost edge 50B. The reference point 50R is provided between the radially outermost edge 50A and the radially innermost edge 50B. However, the reference point 50R can coincide with the radially innermost edge 50B.

A total of the circumferential maximum widths MW1 is equal to or larger than 55 mm. The total of the circumferential maximum widths MW1 is equal to or larger than 60 mm. The total of the circumferential maximum widths MW1 is equal to or larger than 65 mm. In this embodiment, the total of the circumferential maximum widths MW1 is 68 mm. However, the total of the circumferential maximum widths MW1 is not limited to this embodiment and the above ranges.

As seen in FIG. 12, the at least one external spline tooth 40 has an external-spline major diameter DM11. The external-spline major diameter DM11 is equal to or larger than 25 mm. The external-spline major diameter DM11 is equal to or larger than 29 mm. The external-spline major diameter DM11 is equal to or smaller than 30 mm. In this embodiment, the external-spline major diameter DM11 is 29.6 mm. However, the external-spline major diameter DM11 is not limited to this embodiment and the above ranges.

The at least one external spline tooth 40 has an external-spline minor diameter DM12. The at least one external spline tooth 40 has an external-spline root circle RC12 having the external-spline minor diameter DM12. However, the external-spline root circle RC12 can have another diameter different from the external-spline minor diameter DM12. The external-spline minor diameter DM12 is equal to or smaller than 28 mm. The external-spline minor diameter DM12 is equal to or larger than 25 mm. The external-spline minor diameter DM12 is equal to or larger than 27 mm. In this embodiment, the external-spline minor diameter DM12 is 27.2 mm. However, the external-spline minor diameter DM12 is not limited to this embodiment and the above ranges.

The larger-diameter part 42 has an outer diameter DM13 larger than the external-spline major diameter DM11. The outer diameter DM13 ranges from 32 mm to 40 mm. In this embodiment, the outer diameter DM13 is 35 mm. However, the outer diameter DM13 is not limited to this embodiment.

As seen in FIG. 11, the plurality of external-spline driving surfaces 48 each includes a radial length RL11 defined from the radially outermost edge 48A to the radially innermost edge 48B. A total of the radial lengths RL11 of the plurality of external-spline driving surfaces 48 is equal to or larger than 7 mm. The total of the radial lengths RL11 is equal to or larger than 10 mm. The total of the radial lengths RL11 is equal to or larger than 15 mm. In this embodiment, the total of the radial lengths RL11 is 19.5 mm. However, the total of the radial lengths RL11 is not limited to this embodiment.

The plurality of external spline tooth 40 has a radial length RL12. The radial lengths RL12 are respectively defined from the external-spline root circle RC12 to radially outermost ends 40A of the plurality of external spline teeth 40. A total of the radial lengths RL12 is equal to or larger than 12 mm. In this embodiment, the total of the radial lengths RL12 is 31.85 mm. However, the total of the radial lengths RL12 is not limited to this embodiment.

At least one of the at least nine external spline teeth 40 has an asymmetric shape with respect to a circumferential tooth-tip center line CL1. The circumferential tooth-tip center line CL1 is a line connecting the rotational center axis A1 and a circumferential center point CP1 of the radially outermost end 40A of the external spline tooth 40. However, at least one of the external spline teeth 40 can have a symmetric shape with respect to the circumferential tooth-tip center line CL1. The at least one of the at least nine external spline teeth 40 comprises the external-spline driving surface 48 and the external-spline non-driving surface 50.

The external-spline driving surface 48 has a first external-spline-surface angle AG11. The first external-spline-surface angle AG11 is defined between the external-spline driving surface 48 and a first radial line L11. The first radial line L11 extends from the rotational center axis A1 of the bicycle hub assembly 12 to the radially outermost edge 48A of the external-spline driving surface 48. The first external pitch angle PA11 or the second external pitch angle PA12 is defined between the adjacent first radial lines L11 (see, e.g., FIG. 9).

The external-spline non-driving surface 50 has a second external-spline-surface angle AG12. The second external-spline-surface angle AG12 is defined between the external-spline non-driving surface 50 and a second radial line L12. The second radial line L12 extends from the rotational center axis A1 of the bicycle hub assembly 12 to the radially outermost edge 50A of the external-spline non-driving surface 50.

In this embodiment, the second external-spline-surface angle AG12 is different from the first external-spline-surface angle AG11. The first external-spline-surface angle AG11 is smaller than the second external-spline-surface angle AG12. However, the first external-spline-surface angle AG11 can be equal to or larger than the second external-spline-surface angle AG12.

The first external-spline-surface angle AG11 ranges from 0 degree to 10 degrees. The second external-spline-surface angle AG12 ranges from 0 degree to 60 degrees. In this embodiment, the first external-spline-surface angle AG11 is 5 degrees. The second external-spline-surface angle AG12 is 45 degrees. However, the first external-spline-surface angle AG11 and the second external-spline-surface angle AG12 are not limited to this embodiment and the above ranges.

As seen in FIGS. 13 and 14, the brake-rotor support body 34 includes at least one additional external spline tooth 52 configured to engage with the bicycle brake rotor 16 (FIG. 4). In this embodiment, the brake-rotor support body 34 includes an additional base support 54 and a plurality of additional external spline teeth 52. The additional base support 54 has a tubular shape and extends from the hub body 36 along the rotational center axis A1. The additional external spline tooth 52 extends radially outwardly from additional base support 54. A total number of the additional external spline teeth 52 is 52. However, the total number of the additional external spline teeth 52 is not limited to this embodiment.

As seen in FIG. 14, the at least one additional external spline tooth 52 has an additional external-spline major diameter DM14. As seen in FIG. 15, the additional external-spline major diameter DM14 is larger than the external-spline major diameter DM11. The additional external-spline major diameter DM14 is substantially equal to the outer diameter DM13 of the larger-diameter part 42. However, the additional external-spline major diameter DM14 can be equal to or smaller than the external-spline major diameter DM11. The additional external-spline major diameter DM14 can be different from the outer diameter DM13 of the larger-diameter part 42.

As seen in FIG. 16, the hub axle 30 includes an axially contact surface 30B1 to contact the bicycle frame BF. In this embodiment, the axially contact surface 30B1 is contactable with the first frame BF1 of the bicycle frame BF. The first frame BF1 includes a frame contact surface BF12. The axially contact surface 30B1 is in contact with the frame contact surface BF12 in a state where the bicycle hub assembly 12 is secured to the bicycle frame BF with the wheel securing structure WS.

A first axial length AL11 is defined from the axially contact surface 30B1 to the larger-diameter part 42 in the axial direction D2 with respect to the rotational center axis A1. The first axial length AL11 ranges from 35 mm to 41 mm. The first axial length AL11 can be equal to or larger than 39 mm. The first axial length AL11 can also range from 35 mm to 37 mm. In this embodiment, the first axial length AL11 is 36.2 mm. However, the first axial length AL11 is not limited to this embodiment and the above ranges.

The larger-diameter part 42 has an axial end 42A which is the farthest from the axially contact surface 30B1 in the axial direction D2. A second axial length AL12 is defined from the axially contact surface 30B1 to the axial end 42A in the axial direction D2. The second axial length AL12 ranges from 38 mm to 47 mm. The second axial length AL12 can range from 44 mm to 45 mm. The second axial length AL12 can also range from 40 mm to 41 mm. In this embodiment, the second axial length AL12 is 40.75 mm. However, the second axial length AL12 is not limited to this embodiment and the above ranges.

An axial length AL13 of the larger-diameter part 42 ranges from 3 mm to 6 mm. In this embodiment, the axial length AL13 is 4.55 mm. However, the axial length AL13 is not limited to this embodiment and the above ranges.

As seen in FIG. 17, the bicycle rear sprocket assembly 14 comprises at least one sprocket. The at least one sprocket includes a plurality of sprockets. The at least one sprocket includes at least ten sprockets. The at least one sprocket includes at least eleven sprockets. The at least one sprocket includes at least twelve sprockets. The plurality of sprockets includes a largest sprocket SP12. The largest sprocket has a tooth-tip diameter TD1. The plurality of sprockets also includes a smallest sprocket SP1. The smallest sprocket SP1 can also be referred to as a sprocket SP1. The largest sprocket SP12 can also be referred to as a sprocket SP12. In this embodiment, the at least one sprocket further includes sprockets SP2 to SP11. The sprocket SP1 corresponds to top gear. The sprocket SP12 corresponds to low gear. In this embodiment, a total number of the plurality of sprockets is 12. However, the total number of the sprockets of the bicycle rear sprocket assembly 14 is not limited to this embodiment.

The smallest sprocket SP1 includes at least one sprocket tooth SP1B. A total number of the at least one sprocket tooth SP1B of the smallest sprocket SP1 is equal to or smaller than 10. In this embodiment, the total number of the at least one sprocket tooth SP1B of the smallest sprocket SP1 is 10. However, the total number of the at least one sprocket tooth SP1B of the smallest sprocket SP1 is not limited to this embodiment and the above range.

The largest sprocket SP12 includes at least one sprocket tooth SP12B. A total tooth number of the largest sprocket SP12 is equal to or larger than 39. The total tooth number of the largest sprocket SP12 is equal to or larger than 45. A total number of the at least one sprocket tooth SP12B of the largest sprocket SP12 is equal to or larger than 46. The total number of the at least one sprocket tooth SP12B of the largest sprocket SP12 is equal to or larger than 50. In this embodiment, the total number of the at least one sprocket tooth SP12B of the largest sprocket SP12 is 51. However, the total number of the at least one sprocket tooth SP12B of the largest sprocket SP12 is not limited to this embodiment and the above ranges. The tooth-tip diameter TD1 is a diameter of a circle defined by tooth tips of the sprocket teeth SP12B.

The sprocket SP2 includes at least one sprocket tooth SP2B. The sprocket SP3 includes at least one sprocket tooth SP3B. The sprocket SP4 includes at least one sprocket tooth SP4B. The sprocket SP5 includes at least one sprocket tooth SP5B. The sprocket SP6 includes at least one sprocket tooth SP6B. The sprocket SP7 includes at least one sprocket tooth SP7B. The sprocket SP8 includes at least one sprocket tooth SP8B. The sprocket SP9 includes at least one sprocket tooth SP9B. The sprocket SP10 includes at least one sprocket tooth SP10B. The sprocket SP11 includes at least one sprocket tooth SP11B.

A total number of the at least one sprocket tooth SP2B is 12. A total number of the at least one sprocket tooth SP3B is 14. A total number of the at least one sprocket tooth SP4B is 16. A total number of the at least one sprocket tooth SP5B is 18. A total number of the at least one sprocket tooth SP6B is 21. A total number of the at least one sprocket tooth SP7B is 24. A total number of the at least one sprocket tooth SP8B is 28. A total number of the at least one sprocket tooth SP9B is 33. A total number of the at least one sprocket tooth SP10B is 39. A total number of the at least one sprocket tooth SP11B is 45. At least one sprocket has a total tooth number that is equal to or larger than 15. For example, the total tooth number of the sprocket SP4 is 16. The total tooth number of the sprocket SP5 is 18. The total tooth number of the sprocket SP6 is 21. The total tooth number of the sprocket SP7 is 24. The total tooth number of the sprocket SP8 is 28. The total tooth number of the sprocket SP9 is 33. The total tooth number of the sprocket SP10 is 39. The total tooth number of the sprocket SP11 is 45. The total tooth number of the sprocket SP12 is 51. The total number of the sprocket teeth of each of the sprockets SP2 to SP11 is not limited to this embodiment. At least one of the sprockets SP1 to SP12 can include the total tooth number that is equal to or larger than 15.

As seen in FIG. 18, the sprockets SP1 to SP12 are separate members from each other. However, at least one of the sprockets SP1 to SP12 can be at least partly provided integrally with another of the sprockets SP1 to SP12. The bicycle rear sprocket assembly 14 further comprises a sprocket support 56, a plurality of spacers 58, a first ring 59A, and a second ring 59B. The plurality of sprockets SP1 to SP12 are attached to the sprocket support 56 in the illustrated embodiment. For example, the plurality of sprockets SP1 to SP12 is attached to the sprocket support 56 with an adhesive agent.

As seen in FIG. 19, the sprocket SP1 includes a sprocket body SP1A and the plurality of sprocket teeth SP1B. The plurality of sprocket teeth SP1B extends radially outwardly from the sprocket body SP1A. The sprocket SP2 includes a sprocket body SP2A and the plurality of sprocket teeth SP2B. The plurality of sprocket teeth SP2B extends radially outwardly from the sprocket body SP2A. The sprocket SP3 includes a sprocket body SP3A and the plurality of sprocket teeth SP3B. The plurality of sprocket teeth SP3B extends radially outwardly from the sprocket body SP3A. The sprocket SP4 includes a sprocket body SP4A and the plurality of sprocket teeth SP4B. The plurality of sprocket teeth SP4B extends radially outwardly from the sprocket body SP4A. The sprocket SP5 includes a sprocket body SP5A and the plurality of sprocket teeth SP5B. The plurality of sprocket teeth SP5B extends radially outwardly from the sprocket body SP5A. The first ring 59A is provided between the sprockets SP3 and SP4. The second ring 59B is provided between the sprockets SP4 and SP5.

As seen in FIG. 20, the sprocket SP6 includes a sprocket body SP6A and the plurality of sprocket teeth SP6B. The plurality of sprocket teeth SP6B extends radially outwardly from the sprocket body SP6A. The sprocket SP7 includes a sprocket body SP7A and the plurality of sprocket teeth SP7B. The plurality of sprocket teeth SP7B extends radially outwardly from the sprocket body SP7A. The sprocket SP8 includes a sprocket body SP8A and the plurality of sprocket teeth SP8B. The plurality of sprocket teeth SP8B extends radially outwardly from the sprocket body SP8A.

As seen in FIG. 21, the sprocket SP9 includes a sprocket body SP5A and the plurality of sprocket teeth SP9B. The plurality of sprocket teeth SP9B extends radially outwardly from the sprocket body SP9A. The sprocket SP10 includes a sprocket body SP10A and the plurality of sprocket teeth SP10B. The plurality of sprocket teeth SP10B extends radially outwardly from the sprocket body SP10A. The sprocket SP11 includes a sprocket body SP11A and the plurality of sprocket teeth SP11B. The plurality of sprocket teeth SP11B extends radially outwardly from the sprocket body SP11A. The sprocket SP12 includes a sprocket body SP12A and the plurality of sprocket teeth SP12B. The plurality of sprocket teeth SP12B extends radially outwardly from the sprocket body SP12A.

As seen in FIG. 22, the sprocket support 56 includes a hub engagement part 60 and a plurality of support arms 62. The plurality of support arms 62 extends radially outwardly from the hub engagement part 60. The support arm 62 includes first to eighth attachment parts 62A to 62H. The plurality of spacers 58 includes a plurality of first spacers 58A, a plurality of second spacers 58B, a plurality of third spacers 58C, a plurality of fourth spacers 58D, a plurality of fifth spacers 58E, a plurality of sixth spacers 58F, and a plurality of seventh spacers 58G.

As seen in FIG. 23, the first spacers 58A are provided between the sprockets SP5 and SP6. The second spacers 58B are provided between the sprockets SP6 and SP7. The third spacers 58C are provided between the sprockets SP7 and SP8. The fourth spacers 58D are provided between the sprockets SP8 and SP9. The fifth spacers 58E are provided between the sprockets SP9 and SP10. The sixth spacers 58F are provided between the sprockets SP10 and SP11. The seventh spacers 58G are provided between the sprockets SP11 and SP12.

The sprocket SP6 and the first spacer 58A are attached to the first attachment part 62A with a bonding structure such as an adhesive agent. The sprocket SP7 and the second spacer 58B are attached to the second attachment part 62B with a bonding structure such as an adhesive agent. The sprocket SP8 and the third spacer 58C are attached to the third attachment part 62C with a bonding structure such as an adhesive agent. The sprocket SP9 and the fourth spacer 58D are attached to the fourth attachment part 62D with a bonding structure such as an adhesive agent. The sprocket SP10 and the fifth spacer 58E are attached to the fifth attachment part 62E with a bonding structure such as an adhesive agent. The sprocket SP11 and the sixth spacer 58F are attached to the sixth attachment part 62F with a bonding structure such as an adhesive agent. The sprocket SP12 and the seventh spacer 58G are attached to the seventh attachment part 62G with a bonding structure such as an adhesive agent. The sprocket SP5 and the second ring 59B are attached to the eighth attachment part 62H with a bonding structure such as an adhesive agent. The hub engagement part 60, the sprockets SP1 to SP4, the first ring 59A, and the second ring 59B are held between the larger-diameter part 42 and the projecting portion 32B of the lock member 32 in the axial direction D2.

In this embodiment, each of the sprockets SP1 to SP12 is made of a metallic material such as aluminum, iron, or titanium. Each of the sprocket support 56, the first to seventh spacers 58A and to 58G, the first ring 59A, and the second ring 59B is made of a non-metallic material such as a resin material. The sprocket support 56 is made of a non-metallic material including a resin material. However, at least one of the sprockets SP1 to SP12 can be at least partly made of a non-metallic material. At least one of the sprocket support 56, the first to seventh spacers 58A and to 58G, the first ring 59A, and the second ring 59B can be at least partly made of a metallic material such as aluminum, iron, or titanium.

The at least one sprocket includes at least one internal spline tooth configured to engage with the bicycle hub assembly 12. As seen in FIGS. 24 and 25, the at least one sprocket includes at least ten internal spline teeth configured to engage with the bicycle hub assembly 12. The at least one internal spline tooth includes a plurality of internal spline teeth. Thus, the at least one sprocket includes a plurality of internal spline teeth configured to engage with the bicycle hub assembly 12. In this embodiment, the sprocket SP1 includes at least ten internal spline teeth 64 configured to engage with the bicycle hub assembly 12. In this embodiment, the sprocket SP1 includes the internal spline teeth 64 configured to mesh with the external spline teeth 40 of the sprocket support body 28 of the bicycle hub assembly 12. The sprocket body SP1A has an annular shape. The internal spline teeth 64 extend radially inwardly from the sprocket body SP1A.

As seen in FIG. 26, a total number of the at least ten internal spline teeth 64 is equal to or larger than 20. The total number of the at least ten internal spline teeth 64 is equal to or larger than 25. In this embodiment, the total number of the internal spline teeth 64 is 26. However, the total number of the internal spline teeth 64 is not limited to this embodiment and the above ranges.

The at least ten internal spline teeth 64 have a first internal pitch angle PA21 and a second internal pitch angle PA22. At least two internal spline teeth of the plurality of internal spline teeth 64 is circumferentially arranged at a first internal pitch angle PA21 with respect to the rotational center axis A1 of the bicycle rear sprocket assembly 14. At least two internal spline teeth of the plurality of internal spline teeth 64 is circumferentially arranged at a second internal pitch angle PA22 with respect to the rotational center axis A1. In this embodiment, the second internal pitch angle PA22 is different from the first internal pitch angle PA21. However, the second internal pitch angle PA22 can be substantially equal to the first internal pitch angle PA21.

In this embodiment, the internal spline teeth 64 are circumferentially arranged at the first internal pitch angle PA21 in the circumferential direction D1. Two internal spline teeth of the internal spline teeth 64 is arranged at the second internal pitch angle PA22 in the circumferential direction D1. However, at least two internal spline teeth of the internal spline teeth 64 can be arranged at another internal pitch angle in the circumferential direction D1.

The first internal pitch angle PA21 ranges from 10 degrees to 20 degrees. The first internal pitch angle PA21 ranges from 12 degrees to 15 degrees. The first internal pitch angle PA21 ranges from 13 degrees to 14 degrees. In this embodiment, the first internal pitch angle PA21 is 13.3 degrees. However, the first internal pitch angle PA21 is not limited to this embodiment and the above ranges.

The second internal pitch angle PA22 ranges from 5 degrees to 30 degrees. In this embodiment, the second internal pitch angle PA22 is 26 degrees. However, the second internal pitch angle PA22 is not limited to this embodiment and the above range.

At least one of the at least ten internal spline teeth 64 has a first spline shape different from a second spline shape of another of the at least ten internal spline teeth 64. At least one of the at least ten internal spline teeth 64 has a first spline size different from a second spline size of another of the at least ten internal spline teeth 64. At least one of the at least ten internal spline teeth 64 has a cross-sectional shape different from a cross-sectional shape of another of the at least ten internal spline teeth 64. As seen in FIG. 27, however, the internal spline teeth 64 can have the same shape as each other. The internal spline teeth 64 can have the same size as each other. The internal spline teeth 64 can have the same cross-sectional shape as each other.

As seen in FIG. 28, the at least one internal spline tooth 64 comprises an internal-spline driving surface 66 and an internal-spline non-driving surface 68. The at least one internal spline tooth 64 includes a plurality of internal spline teeth 64. The plurality of internal spline teeth 64 includes a plurality of internal-spline driving surfaces 66 to receive the driving rotational force F1 from the bicycle hub assembly 12 (FIG. 6) during pedaling. The plurality of internal spline teeth 64 includes a plurality of internal-spline non-driving surfaces 68. The internal-spline driving surface 66 is contactable with the sprocket support body 28 to transmit the driving rotational force F1 from the sprocket SP1 to the sprocket support body 28 during pedaling. The internal-spline driving surface 66 faces in the driving rotational direction D11. The internal-spline non-driving surface 68 is provided on a reverse side of the internal-spline driving surface 66 in the circumferential direction D1. The internal-spline non-driving surface 68 faces in the reverse rotational direction D12 not to transmit the driving rotational force F1 from the sprocket SP1 to the sprocket support body 28 during pedaling.

The at least ten internal spline teeth 64 respectively have circumferential maximum widths MW2. The internal spline teeth 64 respectively have circumferential maximum widths MW2. The circumferential maximum width MW2 is defined as a maximum width to receive a thrust force F3 applied to the internal spline tooth 64. The circumferential maximum width MW2 is defined as a straight distance based on the internal-spline driving surface 66.

The internal-spline driving surface 66 includes a radially outermost edge 66A and a radially innermost edge 66B. The internal-spline driving surface 66 extends from the radially outermost edge 66A to the radially innermost edge 66B. A second reference circle RC21 is defined on the radially outermost edge 66A and is centered at the rotational center axis A1. The second reference circle RC21 intersects with the internal-spline non-driving surface 68 at a reference point 68R. The circumferential maximum width MW2 extends straight from the radially innermost edge 66B to the reference point 68R in the circumferential direction D1.

The internal-spline non-driving surface 68 includes a radially outermost edge 68A and a radially innermost edge 68B. The internal-spline non-driving surface 68 extends from the radially outermost edge 68A to the radially innermost edge 68B. The reference point 68R is provided between the radially outermost edge 68A and the radially innermost edge 68B.

A total of the circumferential maximum widths MW2 is equal to or larger than 40 mm. The total of the circumferential maximum widths MW2 is equal to or larger than 45 mm. The total of the circumferential maximum widths MW2 is equal to or larger than 50 mm. In this embodiment, the total of the circumferential maximum widths MW2 is 50.8 mm. However, the total of the circumferential maximum widths MW2 is not limited to this embodiment.

As seen in FIG. 29, the at least one internal spline tooth 64 has an internal-spline major diameter DM21. The at least one internal spline tooth 64 has an internal-spline root circle RC22 having the internal-spline major diameter DM21. However, the internal-spline root circle RC22 can have another diameter different from the internal-spline major diameter DM21. The internal-spline major diameter DM21 is equal to or smaller than 30 mm. The internal-spline major diameter DM21 is equal to or larger than 25 mm. The internal-spline major diameter DM21 is equal to or larger than 29 mm. In this embodiment, the internal-spline major diameter DM21 is 29.6 mm. However, the internal-spline major diameter DM21 is not limited to this embodiment and the above ranges. In this embodiment, a ratio of the internal-spline major diameter DM21 to the tooth-tip diameter TD1 ranges from 0.1 to 0.2. The tooth-tip diameter TD1 (FIG. 1) of the largest sprocket SP12 ranges 183.7 mm to 207.9 mm. The ratio of the internal-spline major diameter DM21 to the tooth-tip diameter TD1 ranges 0.14 to 0.17. However, the ratio of the internal-spline major diameter DM21 to the tooth-tip diameter TD1 is not limited to the above ranges.

The at least one internal spline tooth 64 has an internal-spline minor diameter DM22 equal to or smaller than 28 mm. The internal-spline minor diameter DM22 is equal to or larger than 25 mm. The internal-spline minor diameter DM22 is equal to or larger than 27 mm. In this embodiment, the internal-spline minor diameter DM22 is 27.7 mm. However, the internal-spline minor diameter DM22 is not limited to this embodiment and the above ranges.

As seen in FIG. 28, the plurality of internal-spline driving surface 66 includes the radially outermost edge 66A and the radially innermost edge 66B. The plurality of internal-spline driving surfaces 66 each includes a radial length RL21 defined from the radially outermost edge 66A to the radially innermost edge 66B. A total of the radial lengths RL21 of the plurality of internal-spline driving surfaces 66 is equal to or larger than 7 mm. The total of the radial lengths RL21 is equal to or larger than 10 mm. The total of the radial lengths RL21 is equal to or larger than 15 mm. In this embodiment, the total of the radial lengths RL21 is 19.5 mm. However, the total of the radial lengths RL21 is not limited to this embodiment and the above ranges.

The plurality of internal spline teeth 64 has an additional radial length RL22. The additional radial lengths RL22 are respectively defined from the internal-spline root circle RC22 to radially innermost ends 64A of the plurality of internal spline teeth 64. A total of the additional radial lengths RL22 is equal to or larger than 12 mm. In this embodiment, the total of the additional radial lengths RL22 is 27.95 mm. However, the total of the additional radial lengths RL22 is not limited to this embodiment and the above ranges.

At least one of the internal spline tooth 64 has an asymmetric shape with respect to a circumferential tooth-tip center line CL2. The circumferential tooth-tip center line CL2 is a line connecting the rotational center axis A1 and a circumferential center point CP2 of the radially innermost end 64A of the internal spline tooth 64. However, at least one of the internal spline teeth 64 can have a symmetric shape with respect to the circumferential tooth-tip center line CL2. The at least one of the internal spline tooth 64 comprises the internal-spline driving surface 66 and the internal-spline non-driving surface 68.

The internal-spline driving surface 66 has a first internal-spline-surface angle AG21. The first internal-spline-surface angle AG21 is defined between the internal-spline driving surface 66 and a first radial line L21. The first radial line L21 extends from the rotational center axis A1 of the bicycle rear sprocket assembly 14 to the radially outermost edge 66A of the internal-spline driving surface 66. The first internal pitch angle PA21 or the second internal pitch angle PA22 is defined between the adjacent first radial lines L21 (see, e.g., FIG. 26).

The internal-spline non-driving surface 68 has a second internal-spline-surface angle AG22. The second internal-spline-surface angle AG22 is defined between the internal-spline non-driving surface 68 and a second radial line L22. The second radial line L22 extends from the rotational center axis A1 of the bicycle rear sprocket assembly 14 to the radially outermost edge 68A of the internal-spline non-driving surface 68.

In this embodiment, the second internal-spline-surface angle AG22 is different from the first internal-spline-surface angle AG21. The first internal-spline-surface angle AG21 is smaller than the second internal-spline-surface angle AG22. However, the first internal-spline-surface angle AG21 can be equal to or larger than the second internal-spline-surface angle AG22.

The first internal-spline-surface angle AG21 ranges from 0 degree to 10 degrees. The second internal-spline-surface angle AG22 ranges from 0 degree to 60 degrees. In this embodiment, the first internal-spline-surface angle AG21 is 5 degrees. The second internal-spline-surface angle AG22 is 45 degrees. However, the first internal-spline-surface angle AG21 and the second internal-spline-surface angle AG22 are not limited to this embodiment and the above ranges.

As seen in FIG. 30, the internal spline teeth 64 mesh with the external spline teeth 40 to transmit the driving rotational force F1 from the sprocket SP1 to the sprocket support body 28. The internal-spline driving surface 66 is contactable with the external-spline driving surface 48 to transmit the driving rotational force F1 from the sprocket SP1 to the sprocket support body 28. The internal-spline non-driving surface 68 is spaced apart from the external-spline non-driving surface 50 in a state where the internal-spline driving surface 66 is in contact with the external-spline driving surface 48.

As seen in FIG. 31, the sprocket SP2 includes a plurality of internal spline teeth 70. The sprocket SP3 includes a plurality of internal spline teeth 72. The sprocket SP4 includes a plurality of internal spline teeth 74. The first ring 59A includes a plurality of internal spline teeth 76. As seen in FIG. 32, the hub engagement part 60 of the sprocket support 56 includes a plurality of internal spline teeth 78. The plurality of internal spline teeth 70 has substantially the same structure as that of the plurality of internal spline teeth 64. The plurality of internal spline teeth 72 has substantially the same structure as that of the plurality of internal spline teeth 64. The plurality of internal spline teeth 74 has substantially the same structure as that of the plurality of internal spline teeth 64. The plurality of internal spline teeth 76 has substantially the same structure as that of the plurality of internal spline teeth 64. The plurality of internal spline teeth 78 has substantially the same structure as that of the plurality of internal spline teeth 64. Thus, they will not be described in detail here for the sake of brevity.

As seen in FIG. 6, the bicycle rear sprocket assembly 14 further comprises a rear-hub abutment surface 80. The rear-hub abutment surface 80 is configured to abut against the bicycle hub assembly 12 in the axial direction D2 with respect to the rotational center axis A1 of the bicycle rear sprocket assembly 14 in a state where the bicycle rear sprocket assembly 14 is mounted to the bicycle hub assembly 12. In this embodiment, the rear-hub abutment surface 80 abuts against the larger-diameter part 42 of the sprocket support body 28 in the axial direction D2. The rear-hub abutment surface 80 is provided on the hub engagement part 60 of the sprocket support 56. However, the position of the rear-hub abutment surface 80 is not limited to this embodiment.

The largest sprocket SP12 has an axially inner surface SP12C and an axially outer surface SP12D provided on a reverse side of the axially inner surface SP12C in the axial direction D2 with respect to the rotational center axis A1 of the bicycle rear sprocket assembly 14. The axially outer surface SP12D is closer to the rear-hub abutment surface 80 than the axially inner surface SP12C in the axial direction D2.

As seen in FIG. 15, the bicycle hub assembly 12 has an axial center plane CPL that bisects the bicycle hub assembly 12 in the axial direction D2. The axial center plane CPL of the bicycle hub assembly 12 is perpendicular to the rotational center axis A1. As seen in FIG. 6, the axially inner surface SP12C is positioned closer to the axial center plane CPL of the bicycle hub assembly 12 than the rear-hub abutment surface 80 in a state where the bicycle rear sprocket assembly 14 is mounted to the bicycle hub assembly 12. An axial distance AD1 defined between the axially inner surface SP12C and the rear-hub abutment surface 80 in the axial direction D2 is equal to or larger than 7 mm. The axial distance AD1 is equal to or larger than 10 mm. However, the axial distance AD1 is not limited to the above ranges.

As seen in FIGS. 9 and 10, the sprocket support body 28 includes a hub indicator 281 provided at an axial end of the base support 41. The hub indicator 281 is provided in an area of the second external pitch angle PA12 when viewed along the rotational center axis A1. In this embodiment, the hub indicator 281 includes a dot. However, the hub indicator 281 can include other shapes such as a triangle and a line. Further, the hub indicator 281 can be a separate member that is attached to the sprocket support body 28 e.g. with a bonding structure such as an adhesive agent. The position of the hub indicator 281 is not limited to this embodiment.

As seen in FIGS. 26 and 27, the sprocket SP1 includes a sprocket indicator SP1I provided at an axial end of the sprocket body SP1A. The sprocket indicator SP1I is provided in an area of the second internal pitch angle PA22 when viewed along the rotational center axis A1. In this embodiment, the sprocket indicator SP1I includes a dot. However, the sprocket indicator SP1I can include other shapes such as a triangle and a line. Further, the sprocket indicator SP1I can be a separate member that is attached to the sprocket SP1 e.g. with a bonding structure such as an adhesive agent. The position of the sprocket indicator SP1I is not limited to this embodiment. The sprocket indicator SP1I can be provided to any one of other sprockets SP2 to SP12. The sprocket indicator SP1I can also be provided to the sprocket support 56.

Modifications

FIG. 33 illustrates a bicycle rear sprocket assembly 214 in accordance with a modification of the bicycle rear sprocket assembly 14. As seen in FIG. 33, the bicycle rear sprocket assembly 214 comprises the sprocket SP1 and a plurality of sprockets SP202 to SP212. The sprockets SP202 to SP212 have substantially the same structures as those of the sprockets SP2 to SP12. As seen in FIGS. 33 and 34, for example, the sprocket SP212 includes the sprocket body SP12A and the plurality of sprocket teeth SP12B.

One of the sprockets SP202 to SP212 can also be referred to as a first sprocket. Another sprocket adjacent to the first sprocket can also be referred to as a second sprocket. Namely, the at least one sprocket of the bicycle rear sprocket assembly 214 includes the first sprocket and the second sprocket. The first sprocket has a first total tooth number. The second sprocket has a second total tooth number that is smaller than the first total tooth number. The second sprocket is adjacent to the first sprocket in the axial direction D2 without another sprocket between the first sprocket and the second sprocket.

As seen in FIG. 33, for example, the first sprocket SP212 has the first total tooth number that is 51. The second sprocket SP211 has the second total tooth number that is 45. The sprockets SP212 and SP211 can also be referred to as the first sprocket SP212 and the second sprocket SP211. The sprockets SP211 and SP210 can also be referred to as the first sprocket SP211 and the second sprocket SP210. The sprockets SP210 and SP209 can also be referred to as the first sprocket SP210 and the second sprocket SP209. The sprockets SP209 and SP208 can also be referred to as the first sprocket SP209 and the second sprocket SP208. The sprockets SP208 and SP207 can also be referred to as the first sprocket SP208 and the second sprocket SP207. The sprockets SP207 and SP206 can also be referred to as the first sprocket SP207 and the second sprocket SP206. The sprockets SP206 and SP205 can also be referred to as the first sprocket SP206 and the second sprocket SP205. The sprockets SP205 and SP204 can also be referred to as the first sprocket SP205 and the second sprocket SP204. The sprockets SP204 and SP203 can also be referred to as the first sprocket SP204 and the second sprocket SP203. The sprockets SP203 and SP202 can also be referred to as the first sprocket SP203 and the second sprocket SP202. The sprockets SP202 and SP1 can also be referred to as the first sprocket SP202 and the second sprocket SP1.

As seen in FIG. 34, for example, the first sprocket SP212 includes at least one first shifting facilitation area SP212X to facilitate a first shifting operation in which the bicycle chain 20 shifts from the second sprocket SP211 to the first sprocket SP212. The first sprocket SP212 includes at least one second shifting facilitation area SP212Y to facilitate a second shifting operation in which the bicycle chain 20 shifts from the first sprocket SP212 to the second sprocket SP211. In this embodiment, the first sprocket SP212 includes a plurality of first shifting facilitation areas SP212X to facilitate the first shifting operation in which the bicycle chain 20 shifts from the second sprocket SP211 to the first sprocket SP212. The first sprocket SP212 includes a plurality of second shifting facilitation areas SP212Y to facilitate the second shifting operation in which the bicycle chain 20 shifts from the first sprocket SP212 to the second sprocket SP211.

The first sprocket SP212 includes a plurality of first shifting facilitation recesses SP212X1 and a plurality of second shifting facilitation recesses SP212Y1. The first shifting facilitation recess SP212X1 is provided in the first shifting facilitation area SP212X. The second shifting facilitation recess SP212Y1 is provided in the second shifting facilitation area SP212Y.

As seen in FIG. 35, the first shifting facilitation recess SP212X1 is provided on the axially outer surface SP12D to reduce interference between the first sprocket SP212 and the bicycle chain 20 (FIG. 33) in the first shifting operation. The second shifting facilitation recess SP212Y1 is provided on the axially outer surface SP12D to reduce interference between the first sprocket SP212 and the bicycle chain 20 (FIG. 33) in the second shifting operation. The second shifting facilitation recess SP212Y1 is spaced apart from the first shifting facilitation recess SP212X1 in the circumferential direction D1.

As seen in FIG. 36, the plurality of sprocket teeth SP12B of the first sprocket SP212 includes a plurality of shifting facilitation teeth SP212B1 to SP212B3. The shifting facilitation teeth SP212B1 to SP212B3 are provided in the second shifting facilitation area SP212Y. As seen in FIG. 34, the second shifting facilitation area SP212Y is defined by the second shifting facilitation recess SP212Y1 and the shifting facilitation tooth SP212B3 in the circumferential direction D1.

As seen in FIG. 37, the shifting facilitation tooth SP212B1 includes a facilitation recess SP212R1. The shifting facilitation tooth SP212B2 includes a facilitation recess SP212R2. The shifting facilitation tooth SP212B3 includes a facilitation recess SP212R3. The facilitation recess SP212R1 is provided on the axially inner surface SP12C to facilitate derailing of the bicycle chain 20 from the first sprocket SP212 in the second shifting operation. The facilitation recess SP212R2 is provided on the axially inner surface SP12C to facilitate derailing of the bicycle chain 20 from the first sprocket SP212 in the second shifting operation. The facilitation recess SP212R3 is provided on the axially inner surface SP12C to facilitate derailing of the bicycle chain 20 from the first sprocket SP212 in the second shifting operation.

Each of the sprockets SP202 to SP211 has a first shifting facilitation area and a second shifting facilitation area which respectively have substantially the same structures as those of the first shifting facilitation area SP212X and the second shifting facilitation area SP212Y of the first sprocket SP212. They will not be described in detail here for the sake of brevity. The term “shifting facilitation area”, as used herein, is intended to be an area that is intentionally designed to facilitate a shifting operation of a bicycle chain from a sprocket to another axially adjacent sprocket in the area.

As seen in FIG. 38, in the above embodiments, the external spline tooth 40 can include a groove 40G provided between the external-spline driving surface 48 and the external-spline non-driving surface 50 in the circumferential direction D1. The groove 40G reduces weight of the bicycle hub assembly 12.

As seen in FIG. 39, in the above embodiments, the internal spline tooth 64 can include a groove 64G provided between the internal-spline driving surface 66 and the internal-spline non-driving surface 68 in the circumferential direction D1. The groove 64G reduces weight of the bicycle rear sprocket assembly 14.

The term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. This concept also applies to words of similar meaning, for example, the terms “have,” “include” and their derivatives.

The terms “member,” “section,” “portion,” “part,” “element,” “body” and “structure” when used in the singular can have the dual meaning of a single part or a plurality of parts.

The ordinal numbers such as “first” and “second” recited in the present application are merely identifiers, but do not have any other meanings, for example, a particular order and the like. Moreover, for example, the term “first element” itself does not imply an existence of “second element,” and the term “second element” itself does not imply an existence of “first element.”

The term “pair of,” as used herein, can encompass the configuration in which the pair of elements have different shapes or structures from each other in addition to the configuration in which the pair of elements have the same shapes or structures as each other.

The terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein.

Finally, terms of degree such as “substantially,” “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. All of numerical values described in the present application can be construed as including the terms such as “substantially,” “about” and “approximately.”

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein. 

1. A bicycle rear sprocket assembly comprising: at least one sprocket having a total tooth number that is equal to or larger than 15, the at least one sprocket including at least ten internal spline teeth configured to engage with a bicycle hub assembly.
 2. The bicycle rear sprocket assembly according to claim 1, wherein a total number of the at least ten internal spline teeth is equal to or larger than
 20. 3. The bicycle rear sprocket assembly according to claim 2, wherein the total number of the at least ten internal spline teeth is equal to or larger than
 25. 4. The bicycle rear sprocket assembly according to claim 1, wherein the at least ten internal spline teeth have a first internal pitch angle and a second internal pitch angle different from the first internal pitch angle.
 5. The bicycle rear sprocket assembly according to claim 1, wherein the at least one sprocket includes at least ten sprockets.
 6. The bicycle rear sprocket assembly according to claim 1, wherein the at least one sprocket includes at least eleven sprockets.
 7. The bicycle rear sprocket assembly according to claim 1, wherein the at least one sprocket includes at least twelve sprockets.
 8. The bicycle rear sprocket assembly according to claim 1, wherein the at least one sprocket includes a plurality of sprockets and at least one internal spline tooth configured to engage with a bicycle hub assembly, the plurality of sprockets includes a largest sprocket having a tooth-tip diameter, the at least one internal spline tooth has an internal-spline major diameter, and a ratio of the internal-spline major or diameter to the tooth-tip diameter ranges from 0.1 to 0.2.
 9. The bicycle rear sprocket assembly according to claim 1, wherein the at least one sprocket includes: a first sprocket having a first total tooth number; and a second sprocket having a second total tooth number that is smaller than the first total tooth number, the first sprocket includes: at least one first shifting facilitation area to facilitate a first shifting operation in which a bicycle chain shifts from the second sprocket to the first sprocket, and at least one second shifting facilitation area to facilitate a second shifting operation in which the bicycle chain shifts from the first sprocket to the second sprocket.
 10. The bicycle rear sprocket assembly according to claim 1, further comprising a lock member configured to prevent an axial movement of the at least one sprocket mounted on a bicycle hub assembly with respect to a rotational center axis of the bicycle rear sprocket assembly, wherein the lock member includes: a tubular body portion having a center axis; and a projecting portion extending radially outwardly from the tubular body portion with respect to the center axis of the tubular body portion, the tubular body portion has an externally threaded part configured to engage with an internally threaded part of the bicycle hub assembly, and the projecting portion is configured to abut against the at least one sprocket.
 11. The bicycle rear sprocket assembly according to claim 10, wherein the tubular body portion has a first external diameter that is equal to or smaller than 26 mm.
 12. The bicycle rear sprocket assembly according to claim 11, wherein the first external diameter is equal to or larger than 25 mm.
 13. The bicycle rear sprocket assembly according to claim 10, wherein the projecting portion has a second external diameter that is equal to or smaller than 32 mm.
 14. The bicycle rear sprocket assembly according to claim 13, wherein the second external diameter is equal to or larger than 30 mm.
 15. The bicycle rear sprocket assembly according to claim 10, wherein the lock member has a tool engagement portion.
 16. The bicycle rear sprocket assembly according to claim 1, further comprising a sprocket support, wherein the at least one sprocket includes a plurality of sprockets attached to the sprocket support.
 17. The bicycle rear sprocket assembly according to claim 16, wherein the plurality of sprockets is attached to the sprocket support with an adhesive agent.
 18. The bicycle rear sprocket assembly according to claim 16, wherein the sprocket support is made of a non-metallic material including a resin material.
 19. The bicycle rear sprocket assembly according to claim 1, further comprising a rear-hub abutment surface configured to abut against a bicycle hub assembly in an axial direction with respect to a rotational center axis of the bicycle rear sprocket assembly in a state where the bicycle rear sprocket assembly is mounted to the bicycle hub assembly, wherein the at least one sprocket includes a plurality of sprockets including a largest sprocket, the largest sprocket having an axially inner surface and an axially outer surface provided on a reverse side of the axially inner surface in the axial direction, the axially outer surface being closer to the rear-hub abutment surface than the axially inner surface in the axial direction, and an axial distance defined between the axially inner surface and the rear-hub abutment surface in the axial direction is equal to or larger than 7 mm.
 20. The bicycle rear sprocket assembly according to claim 19, wherein the axial distance is equal to or larger than 10 mm.
 21. A bicycle rear sprocket assembly comprising: at least one sprocket having a total tooth number that is equal to or larger than 15, the at least one sprocket including at least one internal spline tooth configured to engage with a bicycle hub assembly, the at least one internal spline tooth having an internal-spline major diameter equal to or smaller than 30 mm.
 22. The bicycle rear sprocket assembly according to claim 21, wherein the internal-spline major diameter is equal to or larger than 25 mm.
 23. The bicycle rear sprocket assembly according to claim 21, wherein the internal-spline major diameter is equal to or larger than 29 mm.
 24. The bicycle rear sprocket assembly according to claim 21, wherein the at least one internal spline tooth has an internal-spline minor diameter equal to or smaller than 28 mm.
 25. The bicycle rear sprocket assembly according to claim 24, wherein the internal-spline minor diameter is equal to or larger than 25 mm.
 26. The bicycle rear sprocket assembly according to claim 24, wherein the internal-spline minor diameter is equal to or larger than 27 mm.
 27. The bicycle rear sprocket assembly according to claim 21, wherein the at least one internal spline tooth includes a plurality of internal spline teeth including a plurality of internal-spline driving surfaces to receive a driving rotational force from the bicycle hub assembly during pedaling, the plurality of internal-spline driving surfaces each includes a radially outermost edge, a radially innermost edge, and a radial length defined from the radially outermost edge to the radially innermost edge, and a total of the radial lengths is equal to or larger than 7 mm.
 28. The bicycle rear sprocket assembly according to claim 27, wherein the total of the radial lengths is equal to or larger than 10 mm.
 29. The bicycle rear sprocket assembly according to claim 27, wherein the total of the radial lengths is equal to or larger than 15 mm.
 30. The bicycle rear sprocket assembly according to claim 21, wherein the at least one sprocket includes at least ten sprockets.
 31. The bicycle rear sprocket assembly according to claim 21, wherein the at least one sprocket includes at least eleven sprockets.
 32. The bicycle rear sprocket assembly according to claim 21, wherein the at least one sprocket includes at least twelve sprockets.
 33. The bicycle rear sprocket assembly according to claim 21, wherein the at least one sprocket includes a plurality of sprockets, the plurality of sprockets includes a largest sprocket having a tooth-tip diameter, and a ratio of the internal-spline major diameter to the tooth-tip diameter ranges from 0.1 to 0.2.
 34. The bicycle rear sprocket assembly according to claim 21, wherein the at least one sprocket includes: a first sprocket having a first total tooth number; and a second sprocket having a second total tooth number that is smaller than the first total tooth number, the first sprocket includes: at least one first shifting facilitation area to facilitate a first shifting operation in which a bicycle chain shifts from the second sprocket to the first sprocket; and at least one second shifting facilitation area to facilitate a second shifting operation in which the bicycle chain shifts from the first sprocket to the second sprocket.
 35. The bicycle rear sprocket assembly according to claim 21, further comprising a lock member configured to prevent an axial movement of the at least one sprocket mounted on a bicycle hub assembly with respect to a rotational center axis of the bicycle rear sprocket assembly, wherein the lock member includes: a tubular body portion having a center axis; and a projecting portion extending radially outwardly from the tubular body portion with respect to the center axis of the tubular body portion, the tubular body portion has an externally threaded part configured to engage with an internally threaded part of the bicycle hub assembly, and the projecting portion is configured to abut against the at least one sprocket.
 36. The bicycle rear sprocket assembly according to claim 35, wherein the tubular body portion has a first external diameter that is equal to or smaller than 26 mm.
 37. The bicycle rear sprocket assembly according to claim 36, wherein the first external diameter is equal to or larger than 25 mm.
 38. The bicycle rear sprocket assembly according to claim 35, wherein the projecting portion has a second external diameter that is equal to or smaller than 32 mm.
 39. The bicycle rear sprocket assembly according to claim 38, wherein the second external diameter is equal to or larger than 30 mm.
 40. The bicycle rear sprocket assembly according to claim 35, wherein the lock member has a tool engagement portion.
 41. The bicycle rear sprocket assembly according to claim 21, further comprising a sprocket support, wherein the at least one sprocket includes a plurality of sprockets attached to the sprocket support.
 42. The bicycle rear sprocket assembly according to claim 41, wherein the plurality of sprockets is attached to the sprocket support with an adhesive agent.
 43. The bicycle rear sprocket assembly according to claim 41, wherein the sprocket support is made of a non-metallic material including a resin material.
 44. The bicycle rear sprocket assembly according to claim 21, further comprising a rear-hub abutment surface configured to abut against a bicycle hub assembly in an axial direction with respect to a rotational center axis of the bicycle rear sprocket assembly in a state where the bicycle rear sprocket assembly is mounted to the bicycle hub assembly, wherein the at least one sprocket includes a plurality of sprockets including a largest sprocket, the largest sprocket having an axially inner surface and an axially outer surface provided on a reverse side of the axially inner surface in the axial direction, the axially outer surface being closer to the rear-hub abutment surface than the axially inner surface in the axial direction, and an axial distance defined between the axially inner surface and the rear-hub abutment surface in the axial direction is equal to or larger than 7 mm.
 45. The bicycle rear sprocket assembly according to claim 44, wherein the axial distance is equal to or larger than 10 mm.
 46. A bicycle rear sprocket assembly comprising: a plurality of sprockets including a largest sprocket, the largest sprocket having an axially inner surface and an axially outer surface provided on a reverse side of the axially inner surface in an axial direction with respect to a rotational center axis of the bicycle rear sprocket assembly; a rear-hub abutment surface configured to abut against a bicycle hub assembly in the axial direction in a state where the bicycle rear sprocket assembly is mounted to the bicycle hub assembly, the axially outer surface being closer to the rear-hub abutment surface than the axially inner surface in the axial direction; and an axial distance defined between the axially inner surface and the rear-hub abutment surface in the axial direction being equal to or larger than 7 mm.
 47. The bicycle rear sprocket assembly according to claim 46, wherein the axial distance is equal to or larger than 10 mm.
 48. The bicycle rear sprocket assembly according to claim 46, wherein the axially inner surface is positioned closer to an axial center plane of the bicycle hub assembly than the rear-hub abutment surface in a state where the bicycle rear sprocket assembly is mounted to the bicycle hub assembly.
 49. The bicycle rear sprocket assembly according to claim 46, wherein a total number of the plurality of sprockets is
 12. 50. The bicycle rear sprocket assembly according to claim 46, wherein a total tooth number of the largest sprocket is equal to or larger than
 39. 51. The bicycle rear sprocket assembly according to claim 46, wherein a total tooth number of the largest sprocket is equal to or larger than
 45. 